1 files changed, 9 insertions, 10 deletions

diff --git a/training/functional.py b/training/functional.py
index 109845b..a2aa24e 100644
--- a/training/functional.py
+++ b/training/functional.py
@@ -335,14 +335,6 @@ def loss_step(
     # Predict the noise residual
     model_pred = unet(noisy_latents, timesteps, encoder_hidden_states).sample
 
-    # Get the target for loss depending on the prediction type
-    if noise_scheduler.config.prediction_type == "epsilon":
-        target = noise
-    elif noise_scheduler.config.prediction_type == "v_prediction":
-        target = noise_scheduler.get_velocity(latents, noise, timesteps)
-    else:
-        raise ValueError(f"Unknown prediction type {noise_scheduler.config.prediction_type}")
-
     if guidance_scale != 0:
         uncond_encoder_hidden_states = get_extended_embeddings(
             text_encoder,
@@ -354,8 +346,15 @@ def loss_step(
         model_pred_uncond = unet(noisy_latents, timesteps, uncond_encoder_hidden_states).sample
         model_pred = model_pred_uncond + guidance_scale * (model_pred - model_pred_uncond)
 
-        loss = F.mse_loss(model_pred.float(), target.float(), reduction="none")
-    elif prior_loss_weight != 0:
+    # Get the target for loss depending on the prediction type
+    if noise_scheduler.config.prediction_type == "epsilon":
+        target = noise
+    elif noise_scheduler.config.prediction_type == "v_prediction":
+        target = noise_scheduler.get_velocity(latents, noise, timesteps)
+    else:
+        raise ValueError(f"Unknown prediction type {noise_scheduler.config.prediction_type}")
+
+    if guidance_scale == 0 and prior_loss_weight != 0:
         # Chunk the noise and model_pred into two parts and compute the loss on each part separately.
         model_pred, model_pred_prior = torch.chunk(model_pred, 2, dim=0)
         target, target_prior = torch.chunk(target, 2, dim=0)